Study On Industrialization Of Ni Based Catalysts For Syngas To Methane

Synthetic nature gas is a clean energy,it has been studied more and more at home and abroad.Methanation catalyst is one of the key technologies in syngas to natural gas,nickel-based catalyst is the most commonly used catalyst for methanation reaction.However,there were few studies on the industrialization of methanation catalysts in China according to the literature.Therefore,the industrialization of nickel-based catalyst is of great significance.On the basis of the previous study of Ni-La/?-Al₂O₃ catalyst,in this paper,the effects of pellet size amplification and preparation scale amplification on the activity and stability of the catalysts were studied.The performance of the catalysts was investigated under the condition of industrial gas.The catalytic reaction kinetic of the catalyst was studied.This research mainly includes the following results:The pellet size of commercial alumina which was used as support was 0.45-1,1-2,2-3,3-4mm,respectively.The catalysts with different pellet size were prepared by incipient impregnation method.The surface area,active component distribution,phase structure and reducibility of the catalysts were studied by N₂ physical adsorption,EDS,XRD and H₂-TPR,and the activity and stability of the catalysts were also investigated.The results showed that the increase of pellet size within the range of the studied pellet size has no significant effect on the conversion of CO and the selectivity of CH₄,but the pellet size of the catalysts increases,and the amount of carbon on the surface of the catalysts increases after reaction,This results in a decrease in the stabilization time of the catalysts.Different scale-up preparation of the catalysts were prepared by incipient impregnation method,respectively,10,100,200,500g,the structure of the four catalysts were compared by characterization.The stability of preliminary amplification of the powder catalyst was investigated,The activity and stability of the four catalysts were evaluated.The results showed that the increase of the preparation scale within the range studied has no significant effect on the conversion of CO and the selectivity of CH₄,but the stability of the catalysts is worse,the rapid deactivation of the catalysts is attributed to the increase of surface carbon of the catalysts by XRD and TG characterization.The kinetic experiments were carried out under the condition of reaction temperature of 250-400?,space velocity of 30000-120000h^-1,H₂/CO ratio of 2.5-3and pressure of 2MPa.The kinetic equation of hyperbolic function was determined by CO hydrogen dissociation reaction mechanism and L-H model.The kinetic parameters were estimated by the least square method and the dynamic equation was solved by MATLAB software.Statistical test and residual analysis of kinetic equation and Arrhenius relationship were carried out by variance analysis.The results showed the kinetic equation fits well and the residual distribution is reasonable,the dynamic equation is reliable and reasonable.